45 lines
2.4 KiB
C
45 lines
2.4 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/fmt/leb128.h"
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/**
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* Decodes a GNU-style varint from a buffer.
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*
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* The GNU Assembler is able to encode numbers this way, since it's used
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* by the DWARF debug format.
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*/
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int unsleb128(const void *buf, size_t size, int128_t *out) {
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int b;
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int128_t r, w;
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unsigned char c;
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const unsigned char *p, *pe;
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pe = (p = buf) + size;
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r = b = 0;
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do {
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if (size && p == pe) return -1;
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c = *p++;
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w = c & 0x7f;
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r |= w << b;
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b += 7;
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} while (c & 0x80);
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if (c & 0x40) r |= -1ull << b;
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if (out) *out = r;
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return p - (const unsigned char *)buf;
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}
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